1. Field of the Invention
The present invention relates to surgically implanted catheter and like tubular devices, specifically to catheters or similar live body implantable devices including means for preventing infectious bacteria and other microorganisms from entering and penetrating into the body through the exit wound site of the implanted device. It is even more specifically in its preferred embodiment directed to a catheter for peritoneal dialysis.
Peritoneal dialysis has offered promise for improving the mobility of patients suffering from kidney disease or failure. Like hemodialysis, peritoneal dialysis involves the diffusional removal of waste products in the patient's blood. Instead of removing and treating the blood outside the body, however, dialysate is introduced directly into the peritoneal cavity by a catheter.
The dialysate fluid remains in the peritoneal cavity for a desired period of time as waste products diffuse from the blood across the peritoneum and into the dialysate. When the dialysate reaches chemical equilibrium, it is removed from the body, fresh dialysate is introduced, and the cycle is repeated.
Peritoneal catheters generally involve a tubular body with one or more dialysate ports outside the patient's body which communicate through the tubular body with the peritoneal cavity. A tunnel cavity is surgically created within the abdominal cutaneous and subcutaneous tissues, including the peritoneum. The catheter is then inserted within the cavity and either stitched to body tissues or anchored in place by the use of porous "cuffs" into which tissue growth is facilitated.
Because peritoneal catheters create a tunnel exit site from the body, there exists a potential for the invasion of infectious bacteria and other microorganisms. Furthermore, the movement of the patient's body from ordinary breathing, walking, and other like activities result in small back-and-forth movements, called "pistoning," of the catheter with respect to the cutaneous and subcutaneous body tissues, which aggravates the risk of bacterial invasion.
Many prior attempts to reduce rates of infections for peritoneal dialysis catheters involve the use of "cuffs"--porous segments fitted annularly around the body of the catheter. After implantation, tissue ingrowth into the porous material anchors the catheter to the body, preventing excessive movement. Additionally, the cuffs act as a putative seal against penetration of infectious microorganisms further into the body.
Catheter designs for peritoneal dialysis are known in the art, as are attempts to reduce the risk of bacterial invasion associated with their use. Illustrative are the designs disclosed in U.S. Pat. No. 5,141,499 to Zappacosta; U.S. Pat. No. 5,098,413 to Trudell, et al.; U.S. Pat. No. 5,057,075 to Moncrief et al.; U.S. Pat. No. 5,049,140 to Brenner et al.; U.S. Pat. No. 4,772,269 and U.S. Pat. No. 4,687,471, both to Twardowski; and U.S. Pat. No. 4,623,329 to Drobish et al.
U.S. Pat. No. 5,141,499 to Zappacosta discloses a U-shaped catheter (10) for peritoneal dialysis With two cuffs (18, 30) and a reduced-diameter tube (16) at the exit site from the body to reduce the area for exit-site tunnel infections.
U.S. Pat. No. 5,098,413 to Trudell et al. discloses a catheter (10) for peritoneal dialysis with a bent shape (29) to reduce catheter movement within the body during dialysate introduction and removal. Two cuffs (30) are used to prevent bacteria ingrowth and to hold the catheter (10) in the body.
U.S. Pat. No. 5,057,075 to Moncrief et al. relates to a method of implanting a peritoneal dialysis catheter with two cuffs, one cuff (2) being adjacent the skin and a peritoneal cuff (24) being anterior to the posterior rectus sheath (23).
U.S. Pat. No. 5,049,140 to Brenner et al. discloses elastomeric fittings (12) of cylindrical shape which are impregnated with antimicrobial agents and fit by radial tension as cuffs over the body shaft (14) of a catheter (10).
U.S. Pat. No. 4,772,269 to Twardowski et al. discloses a peritoneal catheter (10) with a bent segment (24) and two porous cuffs (20, 22) to secure the catheter to the abdominal wall.
U.S. Pat. No. 4,687,471 to Twardowski et al. discloses a peritoneal dialysis catheter (15) with a bent segment (24) and two porous cuffs (20, 22) to secure the catheter to the abdominal wall. The device is substantially similar to U.S. Pat. No. 4,772,269 above, of the same inventor, but includes a flange (38, 48) and a bead (44), the flange oriented at an angle to the axis of the catheter tube (12).
U.S. Pat. No. 4,623,329 to Drobish et al. discloses a tube-in-tube catheter, the outer sleeve (10) of which is permeable by diffusion to an antimicrobial agent contained in the annulus (13) between the inner drainage tube (2) and the outer sleeve (10).
Unfortunately, the practice of using cuffs to reduce the risks of bacterial infection in the catheter suffers from several drawbacks. Although cuffs do provide a measure of resistance to bacterial invasion, they do not prevent bacteria from entering the wound at the exit site, nor do they destroy bacteria traveling along the shaft of the catheter toward the cuffs from the exit site. The use of multiple cuffs to provide "staged" protection against invasion has been suggested. It has also been suggested that the cuffs have antimicrobial agents embedded within their pores as discussed in U.S. Pat. No. 5,049,140 to Brenner et al. The effectiveness of such agents, of course, falls off rapidly as their concentration is reduced over time.
Multiple cuffs provide additional rigidity to the catheter, arising from the greater proportion of the total length of the catheter that is subject to tissue ingrowth into the cuffs. They do little to obviate the disadvantages noted above, however. Because of these failures, multiple cuffs can at best only delay the inevitable need for removal of the catheter arising from infection. When this becomes necessary, the greater tissue ingrowth associated with multiple cuffs impedes and complicates the removal and process. In addition, each removal and replacement operation involves additional trauma for patients already suffering from the loss of renal function.
It is therefore an object of this invention to overcome the disadvantages attendant upon the use of cuffs and to prevent indefinitely the onset of infections in peritoneal dialysis and like catheters, while retaining the advantageous properties and functions thereof. It is a further object of the invention to provide an improved catheter for use in peritoneal dialysis which will withstand a much longer indwelling time within the body before removal is required, thus reducing the trauma to the patient.